Does Vitamin E Prevent or Promote Cancer?

Editor's Comment: Studies conducted on vitamin E's role in preventing cancer have had equivocal results. Some show that vitamin E prevents cancer, others show that it increases the risk of certain cancers. This study shows that vitamin E prevents cancer, but only if it is taken in the mixture (mixed tocopherols) that most resembles what is found in a normal diet.

The cancer preventive activity of vitamin E has been suggested by many epidemiologic studies. However, several recent large-scale human trials with alpha-tocopherol, the most commonly recognized and used form of vitamin E, failed to show a cancer preventive effect. The recently finished follow-up of the Selenium and Vitamin E Cancer Prevention Trial (SELECT) even showed higher prostate cancer incidence in subjects who took alpha-tocopherol supplementation. The scientific community and the general public are faced with a question: “Does vitamin E prevent or promote cancer?” Our recent results in animal models have shown the cancer preventive activity of gamma- and delta-tocopherols as well as a naturally occurring mixture of tocopherols, and the lack of cancer preventive activity by alpha-tocopherol. On the basis of these results as well as information from the literature, we suggest that vitamin E, as ingested in the diet or in supplements that are rich in gamma- and delta-tocopherols, is cancer preventive; whereas supplementation with high doses of alpha-tocopherol is not.

Source: Cancer Prevention Research, 2012; doi:10.1158/1940-6207.CAPR-12-0045. Chung S. Yang, Nanjoo Suh, Ah-Ng Tony Kong. Departments of Chemical Biology and Pharmaceutics, Ernest Mario School of Pharmacy and Center for Cancer Prevention Research, Rutgers, The State University of New Jersey and The Cancer Institute of New Jersey, New Jersey.